Spark-plug.



. A. SCHMIDT.

SPARK PLUG.

APPLICATION FILED MARv 1a. 1912.

1,077,003, Patented Oct. 28, 1913.

UNITED STATES PATENT OFFICE.

ALBERT SCHMIDT, 0F FLINT, MICI-IQN, ASSIGNOR TO CHAMPION IGNITIQN COMPANY, OF FLINT, MICHIGAN, A. CORPORATION OF MICIIIGAN.

SPARK-PLUG.

To all whom t may concern:

Be it known that I, ALBERT SCHMIDT, a citizen of the Republic of France, residing at Flint, in the county of Genesee and State of Michigan, have invented certain new and useful Improvements in Spark-Plugs, of which the following is a spe'ciflcatiom'reference being had therein to the accompany ng drawings.

The invention relates to spark plugs and has particular reference to the construction of the insulator for the electrodes and the manner of securing the same in the metallic casing.

)ne of the principal difiiculties encountered in the construction of spark plugs is the securing of the insulator in position without danger of fracture due either to sudden changes in temperature, unequal expansion and contraction of the insulator and the metallic. casing, and mechanical stresses on the insulator caused by the clamping or securing means.

The present invention is designed to overcome these difficulties primarily by an en- 'gagement between the insulator and its securing means which protects the former from any clamping stresses, and further by Various features as hereinafter set forth.

In the draWings,-Figure 1 is a vertical longitudinal section through the spark plug of my improved construction; Fig. 2 is a perspective View of the insulator with its metallic securing ring; Figs. 3 and at are sections showing the manner of securing the ring to the insulator.

A is the outer metallic casing for the spark plug and B is the insulator, C is a metallic ring surroundingthe insulator B and attached thereto by a grooved bearing which fits over a bead or projection D on the insulatorbody. The method of securing the ring to the insulator is illustrated in Figs. 3 and 4 and as therein shown the ring C is first formed with a shoulder E for bearing on one'side of the bead D and a flange F of sufficient diameter to pass over said head 'as shown in Fig. 3. The parts are then assembled and secured by peening or. spinning down the flange F-as' indicated at G Fig. 4. The result of this operation is not only to firmly attach the ring to the insulator but also due to the fact that the shoulder E has originally a sharp or knife like-edge which during the peening operation is slightly flat- Specification of Letters Batent. Application filed March 16, 1912. Serial No. 684,116.

tened against the insulator surface so as to produce a gasrtight fit.

Patented Oct. 28, 1913.

The rin G has its body portion of greater diameter tian that of the insulator and the shoulders H and I at opposite ends of the ring which bear against the outer metallic case-are out ofalinement with the insulator engaging portion. Thus any clamping stresses to which the ring is subjected will not be transmitted to the insulator and therefore all danger of breaking the illsulator by tightening the casing is avoided. As shown, the shoulder I abuts against a corresponding shoulder J in the casing A, while the shoulder H is engaged by the end of the threaded sleeve K which engages the upper portion of the casing A and forms the clamping member.

In use, the insulator B is held securely Within the cage by its engagement with the ring C while at the same time the amount of contacting surface with the metal is very slight and is located at the point of largest diameter of the insulator body. This permits the insulator and thering to expand and contract as a unit and avoids the danger of breakage frequently occurring at the point of contact between the metal and insulator. l urthermore, the ring G contains only a smallamount of metal and indcpendent of the other metallic parts so that expansion and contraction in the latter will not be transmitted to the ring.

W hat I claim as my invention is: 1. In a spark plug, the combination with a metallic case, of an insulator therein havmg an annular bead or enlargement of its body, a metallic ring surrounding said insulator and. provided with a knife edge shoulder engaging and flattened against oneside of said bead to form a gas-tight joint, the portion of the ring on' the opposite side of said bead being peened down to secure the ring from displacement.

2. In a spark plug, the combination with an insulator having an annular bead or enlargement surrounding the body portion thereof, of a metallic ring surrounding said insulatorhaving a knife edge shoulder flattened against one side 0 said bead or enlargement, the portion of said ring upon the opposite side of said enlargement beingpeened down to permanently secure the ring in position.

3. In a spark plug, the combination with an insulator having an annular bead or enlargement surrounding the body thereof, of a metallic ring of greater diameter than said enlargement provided with a tapering inward projection forming a knife edge bearing for one side of said enlargement, the portion. of said ring upon the opposite side of said enlargement being peened down into. engagement therewith, and a metallic (2186 having clamping" bearings for said ring out of alinement with said head.

l. In a spark plug, the combination'with an insulator having an annular bead or enlargement surrounding the body thereof, of a metallic ring having an inwardly projecting annular bearing for engaging; one side of said bead or enlargement, and a portion upon the opposite side of said bead or enlargement being peened down, said ring In testimony whereof I afiix my signature 25 in presence of two witnesses.

' ALBERT SCHMIDT. Witnesses Mixennn, BRICKER, F. J. UTLEY. 

